@media screen and (min-width: 769px),　print {
    .join_banner {
        display: block;
        position: fixed;
        width: 125px;
        height: 112px;
        bottom: 350px;
        right: 15px;
        z-index: 1000;
    }
}

@media screen and (max-width: 768px) {
    .join_banner {
        display: block;
        position: fixed;
        width: 96px;
        height: 89px;
        bottom: 75px;
        right: 20px;
        z-index: 1000;
    }
}

.join_banner a {
    position: relative;
    display: block;
}

.join_banner img {
    position: absolute;
}